1. Field of the Invention
The present invention relates to a navigation system, remote navigation device and method, and an in-vehicle navigation device, and in particular to an art for reducing communications costs by reducing the amount of data in route guidance data transmitted from a remote navigation device to an in-vehicle navigation device.
2. Description of the Related Art
In recent years, GPS (Global Positioning System) navigation devices have come to be popularly installed in passenger cars and other motor vehicles. A typical in-vehicle navigation device includes an in-vehicle map database (DB) which uses a CD-ROM or a DVD (Digital Video Disk) to enable route guidance display based on the in-vehicle map DB. However, it can not be expected that data for the in-vehicle map DB included in-vehicle navigation devices will be frequently updated and there cases where route guidance for newly established road or facility cannot be executed should be expected. Because of this, attention has been given to systems in which route guidance is executed at the in-vehicle navigation device based on a most recent map, by providing, in addition to the in-vehicle navigation device, a remote navigation device in the form of a route guidance center or the like outside the vehicle, such that route guidance data can be transmitted from the remote navigation device to the in-vehicle navigation device. According to such a system, by updating only the map data at the remote navigation device, route guidance can be executed based on recent map without requiring frequent updates to the in-vehicle map DB.
In the above-mentioned system, an in-vehicle navigation device transmits its current position and destination to a remote navigation device, and requests transmission of route guidance data. In response, the remote navigation device searches routes based on the most recent map and returns the search result to the in-vehicle navigation device.
However, when route guidance data is transmitted for all possible guided routes from the current position to the destination, route guidance data which is not actually needed by the user would also be transmitted. For example, a user would most likely be familiar with the roads near their home, and would therefore not need route guidance by the navigation system in that area. However, in the related art systems, when the area around a user""s home is included in the route guidance from the current position to the destination, the same route guidance is provided as for other areas, resulting in a problem that excessive route guidance data is transmitted from the remote navigation device to the in-vehicle navigation device.
In addition to the area around a user""s home, it is also generally true that a user does not need route guidance by the navigation system for other roads that the user frequently travels on. Therefore, it is desirable to reduce the total amount of data in the route guidance data, and consequently communications cost required for route guidance, by not executing route guidance for areas where guidance is unnecessary, or by only executing route guidance for areas where the operator is certain to require guidance.
Moreover, the above-mentioned system also suffers from the following problem. An in-vehicle navigation device generally includes a route pre-guide function where a route guidance is given as if the vehicle is driven following the route, even when the vehicle is not running. Such a route pre-guide function is used for route confirmation before the vehicle is driven, or for demonstration by a dealer or salesman.
However, if it is intended to simply provide the route pre-guiding function on the system, communications equivalent to when vehicle is driven on all the guided route would be generated between the remote and in-vehicle navigation devices, resulting wasteful communications costs. If the route pre-guide function is employed for route confirmation before driving the vehicle or for demonstration at a dealership, incurring communications costs by displaying route guidance as when the vehicle is actually driven is also wasteful.
The present invention is conceived to solve the above-described problems. One object of the present invention is to provide a navigation system, a remote navigation device and method, and an in-vehicle navigation device which can control the transmission of route guidance data to the in-vehicle navigation device, to thereby reduce the communications cost.
In order to solve the problem described above, according to one aspect of the present invention, there is provided a remote navigation device for transmitting route guidance data to an in-vehicle navigation device, the remote navigation device comprising guide area information obtainer for obtaining guide area information which specifies a map area; route guidance data generating means for generating first route guidance data for the map area specified by the guide area information and second route guidance data for the other map areas, the second route guidance data differing from the first route guidance data in the degree for guidance; and route guidance data transmitting means for transmitting the first and second route guidance data to the in-vehicle navigation device.
According to another aspect of the present invention, there is provided a remote navigation method for transmitting route guidance data to an in-vehicle navigation device, said method comprising a guide area information obtaining step for obtaining guide area information specifying a map area; a route guidance data generating step for generating first route guidance data for the map area specified by the guide area information and second route guidance data for the other map area, the second route guidance data differing from the first route guidance data in the degree of guiding; and a route guidance data transmitting step for transmitting the first and second route guidance data to the in-vehicle navigation device.
According to another aspect of the present invention, there is provided an in-vehicle navigation device characterized in that the device receives first route guidance data for the map area specified by guiding area information and second route guidance data for the other map areas, the second route guidance data differing from the first guiding data in the degree of guiding, and then executes route guidance based on the first and second route guidance data.
According to the present invention, the remote navigation device obtains guide area information, generates first route guidance data for areas specified by the guide area information and second route guidance data for the other areas, the second route guidance data differing from the first route guidance data in the degree of guidance, and transmits the first and second route guidance data to an in-vehicle navigation device. In this manner, when compared to the art described earlier, wherein the same degree of route guidance is executed for all areas from the current position to the destination, the total amount of data in the route guidance data transmitted from the remote navigation device to the in-vehicle navigation device can be decreased by reducing the degree of guidance for a portion of the map area. Consequently, the communications cost can be reduced.
According to another aspect of the present invention, the route guidance data generating means generates route guidance data excluding route guidance for either the map area specified by the guide area information or for all map areas other than that specified by the guide area information. According to this aspect, the route guidance data generated by the remote navigation device excludes either the route guidance for the map area specified by the guide area information or the route guidance for the other map areas. Therefore, by specifying the area where guidance is not needed using the guide area information, route guidance data which does not include the route guidance for that particular area can be transmitted to the in-vehicle navigation device. Alternatively, by specifying the area where guidance is needed using the guide area information, route guidance data can be transmitted to the in-vehicle navigation device which does not include route guidance for areas other than specified. In this manner, the total amount of data for the route guidance data transmitted from the remote navigation device to the in-vehicle navigation device can be reduced.
The guide area information obtaining means may also be configured to receive the guide area information from the in-vehicle navigation device. This facilitates execution of route guidance corresponding to each vehicle.
In a case where the guide area information specifies the area where guidance is not needed, this area where guidance is not needed can be set to, for example, the area near the user""s home. In this manner, communications costs can be reduced by avoiding execution of route guidance for the areas around home where route guidance is usually not necessary.
Moreover, the guide area information can be configured to be set based on a history of the routes along which the vehicle has been driven. In this manner, communications cost can be reduced by not executing route guidance for, for example, a route in which the vehicle has been driven for more than predetermined times or a route in which the vehicle is driven in a predetermined period.
According to another aspect of the present invention, there is provided an in-vehicle navigation device for receiving route guidance data from the remote navigation device, the in-vehicle device comprising, guide area information setting means for setting guide area information which specifies a map area, and guide area information transmitting means for transmitting the guide area information to the remote navigation device. According to the in-vehicle navigation device, necessary and sufficient route guidance for each vehicle can be received.
According to another aspect of the present invention, there is provided a navigation system comprising a remote navigation device and an in-vehicle navigation device, in which the in-vehicle navigation device executes route guidance based on route guidance data transmitted from the remote navigation device, wherein, the in-vehicle navigation device includes means for transmitting a route pre-guide request to the remote navigation device, and the remote navigation device, upon receiving the route pre-guide request from the in-vehicle navigation device, transmits route pre-guide data containing guidance content with less information than a route guidance based on the route guidance data, to the in-vehicle device.
According to another aspect of the present invention, there is provided a remote navigation device for transmitting, to an in-vehicle navigation device, route guidance data which forms a basis for route guidance by the in-vehicle navigation device, the remote navigation device comprising route pre-guide request receiving means for receiving a route pre-guide request form the in-vehicle navigation device and route pre-guide data transmitting means for transmitting, upon receiving the route pre-guide request from the in-vehicle navigation device, route pre-guide data which contains guidance content with less information than that in a route guidance based on the route guidance data, to the in-vehicle navigation device.
According to another aspect of the present invention, there is provided a remote navigation method for transmitting, to an in-vehicle navigation device, route guidance data which forms a basis for the in-vehicle navigation device executing route guidance, the method comprising a route pre-guide request receiving step for receiving a route pre-guide request from the in-vehicle navigation device and a route pre-guide data transmitting step for transmitting, upon receiving the route pre-guide request from the in-vehicle navigation device, to the in-vehicle navigation device, route pre-guide data which contains guidance content with less information than route guidance based on the route guidance data.
According to another aspect of the present invention, there is provided an in-vehicle navigation device comprising route guidance data receiving means for receiving route guidance data; route guidance means for executing route guidance using the route guidance data; route pre-guide request transmitting means for transmitting a route pre-guide request to the remote navigation device; route pre-guide data receiving means for receiving route pre-guide data in response to the route pre-guide request, the route pre-guide data containing guidance content with less information than in a route guidance based on the route guidance data; and route pre-guiding means for executing route pre-guide based on the route pre-guide data.
According to the present invention, a route pre-guide can be executed at an in-vehicle navigation device, which is useful for route confirmation by a user and for demonstration by a dealer. The route pre-guide is executed based on the route pre-guide data received from a remote navigation device. The route pre-guide data contains less content than the normal guidance data for the same route.
Upon receiving a route pre-guide request from an in-vehicle navigation device, a remote navigation device transmits, instead of the normal route guidance data, route pre-guide data which contains guidance content with less information. In this manner, a problem in which the same communications costs are incurred for route pre-guide as for normal route guidance can be avoided.
The remote navigation device, when receiving a route pre-guide request, can reduce the amount of data for route guidance data by setting a scale for the route guidance data based on, for example, the distance from the current position of the vehicle to a characteristic point on the guided route. More specifically, the amount of data for the route guidance data can be reduced by, for example, executing more detailed route guidance only when the distance to a guided point is short.